Abstract

Background : The exact pro-oxidant and antioxidant status in osteoarthritis patients is still not clear. To add a new insight to the question, changes in the erythrocyte lipid peroxidation products (MDA), levels of glutathione (GSH), ascorbic acid and plasma vitamin E (nonenzymatic antioxidant parameters); and activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase in erythrocytes and plasma glutathione - S - transferase (GST) were measured in patients with osteoarthritis. Aim: This work was undertaken to assess oxidative stress and antioxidant status in patients with osteoarthritis. Settings and design: The study was conducted in 20 patients and compared to controls. Levels of erythrocyte MDA, GSH, ascorbic acid, plasma vitamin E; and activities of antioxidant enzymes were measured in patients with osteoarthritis. materials and Methods: Erythrocyte GSH was measured by the method of Beutler et al. Ascorbic acid levels were measured by the method of Tietz. Plasma vitamin E levels were measured by the method of Baker et al. MDA was determined as the measure of thio barbituric acid reactive substances (TBARS). SOD activity in the hemolysate was measured by the method of Misra and Fridovich. Activity of catalase was measured by the method of Beers and Sizer. GPX activity was measured as described by Paglia and Valentine in erythrocytes, and Plasma GST activity was measured as described by Warholm et al. These parameters were measured in 20 patients and compared to controls. Statistical analysis: Statistical analysis between group 1 (controls) and group 2 (patients) was performed by the student's t - test using the stat -view package. Results: It was observed that there was a significant increase in erythrocyte MDA levels; SOD, GPX and plasma GST activities; and a significant decrease in erythrocyte GSH, ascorbic acid, plasma vitamin E levels and catalase activity in patients with osteoarthritis when compared to controls. Conclusions: The results of our study suggest higher oxygen-free radical production, evidenced by increased MDA and decreased GSH, ascorbic acid, vitamin E and catalase activity, support to the oxidative stress in osteoarthritis. The increased activities of antioxidant enzymes may be a compensatory regulation in response to increased oxidative stress.

Arthritis, a joint inflammation, refers to a group of diseases that cause pain, swelling, stiffness and loss of motion in the joints. Osteoarthritis is the most common form of arthritis and is a disease of cartilage degeneration.[1] Osteoarthritis, also known as degenerative joint disease, is a process of progressive deterioration of articular cartilage and formation of new bone (osteophyte) at the joint surface. Lipid peroxidation mediated by free radicals is considered to be the major mechanism of cell membrane destruction and cell damage. Free radicals are formed in both physiological and pathological conditions in mammalian tissues.[2] The uncontrolled production of free radicals is considered an important factor in the tissue damage induced by several pathophysiologies.[3],[4] Alteration in the oxidant-antioxidant profile is known to occur in rheumatic diseases.[5],[6] Oxidative stress due to damage brought about by free radicals is also known to influence the response of these patients to therapy. Moreover, the body's defense mechanisms would play an important role in the form of antioxidants and try to minimize the damage, adapting itself to the above stressful situation. Antioxidants are compounds that dispose, scavenge and suppress the formation of free radicals or oppose their actions,[7] and two main categories of antioxidants are those whose role is to prevent the generation of free radicals and those that intercept any free radicals that are generated.[8] They exist in both the aqueous and membrane compartment of cells and can be enzymes or non-enzymes.

In the present study, the following parameters were assessed in erythrocytes and plasma to elucidate the oxidant-antioxidant status in patients with osteoarthritis. Erythrocyte MDA levels were measured as TBARS, which serve as an index of the extent of lipid peroxidation. Erythrocyte GSH, ascorbic acid and plasma vitamin E serve as non-enzymatic antioxidant parameters. The activities of antioxidant enzymes SOD, catalase, GPX in erythrocytes and GST in plasma were measured. GST is an enzyme involved in antioxidant defense and also in detoxification.